196 – Joe’s #5 Cylinder Mystery

Airplane Owner Maintenance - By Dean Showalter

This fuel injector line must have only been attached finger tight when the fuel injectors were reinstalled after cleaning. The engine ran fine at first, but all of a sudden during one engine run, the #5 EGT took a nose dive, and the #5 CHT immediately started dropping off as well.

The above photo was taken AFTER we discovered what the problem was. I’m guessing the nut was not tight, and it worked itself loose, causing the cylinder to immediately cease firing, since the fuel was no longer being sprayed into the injector nozzle.

Joe hired me to help troubleshoot the situation. We got on a Face Time call, and I asked him to show me the #5 induction pipe and coupling area, and all of a sudden, he noticed the #5 fuel injector line was not attached…

I was sure this was the culprit, and we were both thrilled to have solved the mystery. In our minds, it would be a simple fix, and Joe would be back in the air again.

Not so fast… since the cowling was off, Joe decided to inspect all the cylinders with his borescope. And that’s when he noticed a bigger problem. Joe noticed the exhaust valve in cylinder #2 did not look good, and he sent me some photos.

That is a really bad looking exhaust valve, with three green edges… one at 1 o’clock, one at 4 o’clock and one at 9 o’clock. The edge at 1 o’clock even looks like it has a scalloped edge, a sure sign it is severely worn.

This valve is too far gone, and is not a candidate for lapping in place. The cylinder needs to come off.

Wow, maybe the issue Joe had with the #5 cylinder was a blessing in disguise, since it prompted him to borescope all his cylinders, and that’s when he found the burning exhaust valve in cylinder #2.

Well done Joe! I’m glad you found these issues before they became an inflight emergency.

---

A borescope is a necessary tool in maintaining piston engine cylinders, and they are surprisingly affordable these days. I recommend the Vividia VA-400 from Oasis Scientific. It’s the one I use. If you’re considering a borescope you may be asking, “Which borescope should I buy?” This is a great question, and I did a podcast episode about it a good while back. It’s episode 115, and you can find it here: “115 – Which Borescope Should I Buy?”

If you decide to buy a Vividia VA-400 (or another model by Oasis Scientific,) you can check it out here:

Vividia VA-400 Borescope

And remember to use the code “Dean” for a 10 % discount. (This code only works when purchasing from Oasis Scientific, and I appreciate you doing this, because it helps me out as well.)

---

Ways you can work with me:

1. Hire me to review your borescope photos.
2. Hire me to do maintenance records research.
3. Hire me for one-on-one consulting.

The details and pricing for these services are on the store page of my website:

http://www.airplaneownermaintenance.com/store

Video training courses:

Safety Wire Like A Pro!

Landing Gear Shock Strut Servicing

---

The post “196 – Joe’s #5 Cylinder Mystery” appeared first at AirplaneOwnerMaintenance.com